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  1. Today
  2. I'm sure the answer to this will be something so easy, obvious, and profoundly stupid that my family and friends will all disavow having ever known me, but I'm stymied. I am using an animated noise to create a lumpy VDB fog field, which I convert to SDF and then use VDB Combine to cut out part of a hero model. I'm cutting it into two interlocking parts, using SDF Union Subtract for one side and SDF Union Intersection for the other, and I will subsequently assign a different material to each part. Originally I got it set up, no problem, with a standard AAnoise. I'm trying to get it set up with a periodic noise so I can loop it. The problem is that at the VDB combine stage, it doesn't subtract or intersect cleanly. You can tell something is happening, as there are little dotted lines on the resulting surface, and the occasional hole, but it's not cutting it out like I would like. I've tried different resolutions with the VDB from Polygons and that doesn't seem to make a difference. (I've actually run into this before, but I'll either rebuild the Volume VOP or fudge some numbers and it goes away. No such luck here.) What obvious, stupid thing am I doing wrong so that the VDB combine isn't working like I'm hoping? Thanks for help and forebearance! sdf_union_problems.hiplc
  3. FLIP Particles sticking on a animated surface (And staying there!)

    Just to continue updating this while I try to find a solution here's what I come across for resources: Been on the hunt for something that something sticks to an animated surface with velocity and doesn't full off unless it's set to. It'll also need to resolve quickly, because it will be used for animation. (The below all include .hip files that work on H18) 1) This method uses a popdrag for air resistance plus some other methods that work well to keep particles smoothly flowing across a surface. Suffers from animation really throwing it out of wack. When particles fell off the surface because of rotation in animation from the collision object it caused them to have very strange behavior (They kind of just flated in the air in a strange pattern). I didn't dig too much into this, but didn't seem very CPU taxing and did do a good job of smoothly flowing surfaces. https://www.sidefx.com/forum/topic/24897/ (Hip File) https://www.sidefx.com/forum/attachment/2540103a248b6325ae9c84345748756cbb800e33/ 2) A method that converts your geo to a fog density, uses a volume wrangle to control the density of the fog and uses that as a stick mask. Seems to be a bit more of a taxing method as the default sims example are simple, yet take a while per frame then other methods listed. May of just been the scene setup. Works well, but a simple rotation caused all particles fall off. Had great sticking effects with good control, but I wasn't able to easily find a method to get these to stick to an animated surface during a 180 rotation on the sphere. https://www.sidefx.com/forum/topic/33954/ (Hip file) https://www.sidefx.com/forum/attachment/dc1b85ffd5ead04d635ddb117ec8eff5e3d81399/ 3) Looking somewhat similar to the 2nd method above, converts an area to a gas field and uses that as a stick mask. Goes about it a bit different way - blasts off the section and uses a pryo node to turn it into density, but like the first method, a rotation caused particles to fall out. Scene simmed pretty fast, maybe due to the areas of selection being converted to a fog being smaller.. (Hip file) https://forums.odforce.net/applications/core/interface/file/attachment.php?id=44804 4) Particles really *stick" right where they hit, and the sim was very quick. Doing a rotation did cause them to come off, it didn't make all of them. I'll have to mess around some more with the settings on this. Uses a Geometry VOP DOP and sample collision field for every particle . Might start digging into this method. (Hip File) https://forums.odforce.net/applications/core/interface/file/attachment.php?id=17044 5) Have not tested this yet because it's not free. Considering picking this up but not sure if it would work for me. It's a scene for $33. It's more about surface adhesion versus *sticking* though so it may not have what I need. Can't speak to much becasue I haven't used it. Benchmarks show it to resolve pretty quickly though and add very little onto total sim times. https://gumroad.com/l/Oejcb
  4. Yesterday
  5. Control forces by conditions

    Hey I had this come up a few times today and I was wondering what was the best way to tackle it. I am doing a melting sim of an object thats floating in space. I am using temperature to heat the FLIP and start the melting process. if use gravity then the whole thing starts moving from the start and not just the heated parts. I was thinking if I could just apply the forces based on temperature then that would would be ideal. I tried something like this in the pop wrange but its giving me erratic results. float hot = @temperature; if (hot>1) {@v *= 3;}; Also whats the equivalent of the the geometry spreadsheet in dops, if I wanted to see the values of the temperature or any attribute. I can visualize as color but would be nice to get some numbers. Cheers!
  6. Hey, sry for asking again... I did lots of tutorials about python basisc the last days and I get more into it. I had a running "Create folders Script" working and right now I try to move all the code into an HDA / Python Modul. But suddenly I dont get the labels of my ordered menu and also the numbers dont start from 1, but from 0... The only thing I actually did, was to copy the code from the NULL into the HDA Module and the parameters are in a subfolder to get more order inside the HDA. The others functions work just fine and do as they should - just the "create_project_folders" function doesnt work. Is there some syntax or logical problem? Thx edit: Scene/HDA files added. create_project_v001.hdalc create_project_v001.hiplc
  7. crazy bright spots in volume

    Maybe try to clamp the volume rather than absolute value. I know volumes can render strangely with negative values.
  8. vellum weld selected edges

    Thank you! I should have tried it on a simple geo like yours. It was basically an issue with the geo.
  9. (SOLVED)POP: Rotating instanced geometry help

    Oh, haha ignore that chop! At first, I tried randomizing them a different way, but that chop isn't being used. All the work is now being done easily with that pop drag spin.
  10. vellum weld selected edges

    but......it just works... vu_Weld.hiplc
  11. wow this solution was amazing!! thanks! i hardly would approach this in such clever way. i wondering about this chop inside dop, what is exactly doing??
  12. (SOLVED)POP: Rotating instanced geometry help

    Wrangling angular velocity should work with pops. Here's a slight modification to your file. I've given each particle an initial random direction in SOPS then used the POP drag spin node to do the random spinning in DOPs. geoinstance_rotationv00-jt.hip
  13. Random link of interest

    Simple particle rules + time = life ?!
  14. This is one way to resize a vdb with bounds and combine_vdb. Resize_vdb.hip
  15. Hello guys i with a scene that has bunch of swords falling, they do not need to colide or something. i using a Pop solver with simple points falling, then i attached an copy sop to actually plug the incoming geometry. the point is, they are just falling like freezed/boring, no rotation. i've tried wrangle an angular velocity but it seems is just not work with Pop's. how to given them rotating effect with random direction for particle for sure. thanks in advance. ps: i've attached an simples setup. geoinstance_rotationv00.hip
  16. How to add color gradient through velocity plus collision to influence color velocity? to influence the color such as this one here: https://vimeo.com/59024762 how did he do, but he used xsi softimage. if possible to make a Houdini?
  17. thank you, VDB only takes keeps voxels that have a density threshold higher than a default (very small value), and deletes the rest. That I know. But I started from a box, so no matter how clever the vdb is, the box is limiting it (used polygon box then created vdbfrompolygon). That's what I want to avoid since I'm applying a noise that goes beyond the box but gets clipped by the box boundaries. The question is how to give the vdb more room so the noise can express itself with freedom and not get oppressed by the boundaries of the box?
  18. vellum weld selected edges

    Hey I was wondering if any one knew, when you take a geo and shatter or fracture it into pieces. The weld constraint in vellum seems to know exactly how to attach them back together. However I have a piece of geo thats presplit along the edges along the edges in a specific pattern and I can seem to get the weld to recognise the edges and weld them together. I have created a group (in both edges and points) thats just the outer edges I thought that would work but no dice. Thanks
  19. Exterior Band voxel is relative to SDF (Distance VDB), not Fog. Band voxels isn't for volume resizing. May be you should take a look at some tutorials that explains how VDB work.
  20. Muscle Rig (frankenmuscle)

    Hey there people, so I encountered a problem with my rig. The way i understand it is that i need to turn this rig into bones. Does somebody know how to turn the rig in the clip to bones with twist effectors? The thing is the muscles are only moved by the arm and not the chest. I've tried changing the null in type properties to take in more inputs so that the muscle pin is also effected by the movement of the chest, but no luck there because the type properties are locked. Never mind, i didn't think of the possibility of connecting the pins to the chest controller itself.
  21. is there a way to have the node information open permanently as a tab in the interface, just like the geometry spreadsheet?
  22. Hi everyone, I have been looking to create slow-motion flip sim using a narrow band tank and dropping an RBD object into it. I have seen older advice like this from Atom about adjusting the Time Scale inside the Flip solver: https://vimeo.com/121376943 But when I followed the instructions it doesnt seem to work - as its many versions old from the current H18 there could be a lot of reasons for this. Does anyone have any up to date information of how to achieve this? Currently I am going round in circles adjusting the Velocity Scale and Time Scale in a never ending fight to get it to slow down correctly but also maintain the splash velocity. I cant seem to get the flip sim to match the Time Scale of my RBD at all, the flip is always moving way too fast. Any help would be great!
  23. I started making a grass Pack

    Thanks, that's nice of you to say
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